The present disclosure relates to processes useful in providing toners suitable for electrostatographic apparatuses, including xerographic apparatuses such as digital, image-on-image, and similar apparatuses.
Numerous processes are known for the preparation of toners, such as, for example, conventional processes wherein a resin is melt kneaded or extruded with a pigment, micronized and pulverized to provide toner particles. There are illustrated in U.S. Pat. Nos. 5,364,729 and 5,403,693, the disclosures of each of which are hereby incorporated by reference in their entirety, methods of preparing toner particles by blending together latexes with pigment particles. Also relevant are U.S. Pat. Nos. 4,996,127, 4,797,339 and 4,983,488, the disclosures of each of which are hereby incorporated by reference in their entirety.
Toner systems normally fall into two classes: two component systems, in which the developer material includes magnetic carrier granules having toner particles adhering triboelectrically thereto; and single component systems (SDC), which typically use only toner. Placing charge on the particles, to enable movement and development of images via electric fields, is most often accomplished with triboelectricity. Triboelectric charging may occur either by mixing the toner with larger carrier beads in a two component development system or by rubbing the toner between a blade and donor roll in a single component system. Toners should also display acceptable triboelectric properties, which may vary with the type of carrier or developer composition.
Toners useful for xerographic applications should possess certain properties relating to storage stability and particle size integrity. That is, the particles should remain intact and not agglomerate until they are fused on paper. Due to energy conservation measures, and more stringent energy characteristics placed on xerographic engines, such as on xerographic fusers, it may be desirable to reduce the fixing temperatures of toners onto paper, thereby reducing power consumption and extending the lifetime of the fuser system.
For a contact fuser, that is, a fuser which is in contact with the paper and the image, the toner should not substantially transfer or offset onto the fuser roller, referred to as hot or cold offset depending on whether the temperature is below the fixing temperature of the paper (cold offset), or whether the toner offsets onto a fuser roller at a temperature above the fixing temperature of the toner (hot offset).
Toners that may be used at desirable fusing temperatures, possessing properties including excellent document offset and heat cohesion, remain desirable.